The present invention relates to noctilucent polyurethane chips and a method of manufacturing the same, and more particularly to noctilucent polyurethane chips and their manufacturing method by using waste polyurethane and photoluminescent pigments, to care for natural resources and prevent environmental pollution and to provide pedestrians and drivers or bicycle riders with safe passage on streets and roads at night as well.
As an industrial waste obtain able from soles for shoes, parts for refrigerators or cars, etc., waste polyurethane which is synthetic rubber of high quality has a high possibility of recycling. However, conventionally, the waste polyurethane has been incinerated or buried and barely have been recycled, due to the domestic restrictions in marketability and economical usefulness.
Meanwhile, various attempts to develop methods of recycling or disposing waste tires have been sought, among which there are method of recycling waste tires in their original form as in case of building up military camp sites, public works, reclamation or piling up; method of thermally processing waste tires as in case of cement kiln, dry distillation and heat decomposition; and method of processing waste tires to recycled activated charcoal and rubber powder.
The above method of recycling waste tires in their original form, however, had disadvantages in that tires are not easily biodegradable and thus the problem of environmental pollution can last for a long time. Also, the method of thermally processing waste tires had problem that it may generate sources of secondary pollution during the heat treatment. Therefore, in view of protecting environment, the method of processing waste tires has been preferred.
One example of the method of processing waste tires is disclosed in Korean Patent Application Nos. 2002-10319 and 2002-10320 entitled xe2x80x9cresilient pavement using waste tires and waste urethane rubber chips and a method of construction thereofxe2x80x9d. The pavement disclosed in the above patent applications comprises a lower supporting layer and an upper resilient layer, the lower supporting layer comprising 70-80% by weight of fine aggregates (gravel) having average particle diameter of 6-10 mm and 20-30% by weight of rubber chips of pulverized waste tires having particle diameter of 4-8 mm, and the upper resilient layer mainly comprising color rubber chips of waste urethane cut in the particle diameter of 3-4 mm. Further, the method of constructing the pavement comprises hardening a construction site to be flat, constructing a primer layer, dispersing the material for the lower supporting layer, and before the material for the lower supporting layer is hardened, dispersing the material for the upper resilient layer.
However, because the pavement which used waste tire chips had limitations in that the physical properties of the pavement such as constriction and expansion coefficient or weather resistance were different from those of adhesives (binding agent), the pavement had inferior durability and its color was dark and monotonous.
In addition, the resilient rubber pavement had disadvantages that its manufacturing procedure was complicated and smelled bad in summer.
In the meantime, as the pavement for sidewalks, bicycle ways, promenades of parks, exercising roads and so on, concrete which is a mixture of stones and cement has been used. Sometimes, color concrete, porous concrete and asphalt concrete, etc. have been used. However, the concrete pavement had disadvantages in that it was too strong that the impact on peoples"" knees on landing while walking or running on the pavement was too great. Also, concrete paving bricks and color concrete pavement were easily destroyed by even a slight impact thereon and they were lacking in resiliency and had poor shock absorption, although they were excellent in hardness, heat resistance and weather resistance.
In addition, conventional pavement for sidewalks, bicycle ways, promenades of parks and exercising roads, which uses concrete and waste tire rubber chips, was dark. Therefore, it caused inconvenience and danger to pedestrians or drivers or bicycle riders since they could not easily distinguish road and street, especially when it was raining or at night. As a result, pedestrians, drivers or riders were exposed to accidents more frequently.
Accordingly, the inventor of the present invention studied and researched into pavement materials and methods of manufacturing the same by using recycled waste polyurethane obtained from soles of shoes, parts of refrigerators and vehicles, etc. and decrepit (recycled) polyurethane resilient pavement, and also using phosphorescent substance. As a result, the inventor completed the present invention which provides resiliency while walking and enables pedestrians, drivers or riders to clearly distinguish streets and roads even at night or while raining, thereby significantly reducing the anger of accidents.
The phosphorescent substance is phosphorescent body, which maintains luminescence even in the absence of light. Examples of the phosphorescent body are jewelry, sulfides, sulfides of alkali earth metals, zinc sulfides containing heavy metals, aluminates with rare earth elements added, etc. The phosphorescent body is usually used for luminous marks (e.g., marks for switches, plug sockets, products for use in a dark room, parapets and wall marks), photoluminescent marks (e.g., marks for exits, emergency exit doors, fire hydrants and fire alarms) and ornaments (e.g., for ash trays, lighters, necklaces and tiles).
The object of the present invention is to provide noctilucent polyurethane chips and a method of manufacturing the same, which enable the energy accumulated during the daytime to radiate and emit light in dark place, thus providing pedestrians, drivers or bicycle riders with clear sights even at night or while raining, thereby significantly reducing the danger of accidents.
Another object of the present invention is to provide noctilucent polyurethane chips and their manufacturing method by using waste polyurethane obtained from soles of shoes, parts of refrigerators and vehicles, etc. and decrepit (recycled) polyurethane resilient pavement, thus nursing resources and preventing environmental pollution.
A further object of the present invention is to provide noctilucent polyurethane chips having aesthetic view and excellent functionality, by using phosphorescent substances as a raw material of pavement.
In order to achieve the above objects, the method of manufacturing noctilucent polyurethane chips comprises the steps of:
preparing waste polyurethane scraps by collecting coarse waste polyurethane scraps from soles of shoes, parts of refrigerators and vehicles, decrepit polyurethane resilient pavement, etc. (hereinafter referred to as xe2x80x9cwaste polyurethane scrapsxe2x80x9d), separating the scraps according to their colors and removing impurities stuck to the scraps;
pulverizing the prepared waste polyurethane scraps in a predetermined size;
based on 100 kg of the pulverized waste polyurethane scraps, adding 2-5 kg of stearic acid as a melting agent, 1-10 kg of a photoluminescent pigment, 1-3 kg of a flame retardant, 0.1-1 kg of titanium dioxide as a decolorant, and 10-30 kg of heavy calcium carbonate as a brightness adjusting agent, and mixing them by stirring and then extruding through an extruder; and
cutting the extruded polyurethane in particle diameter of 3-10 mm.
The noctilucent waste polyurethane chips according to the present invention are those obtained through the above manufacturing steps.
A method of constructing noctilucent resilient pavement by using the noctilucent polyurethane chips obtained by the above manufacturing method comprises the steps of:
removing moisture or impurities on a surface to be paved;
applying a primer layer uniformly on the surface to be paved to secure firm binding between the surface to be paved and the noctilucent polyurethane chips;
blending the noctilucent polyurethane chips with a polyurethane binder by eight ratio of 100:20-40 and applying the blended mixture of the noctilucent polyurethane chips on the surface to be paved uniformly;
pressing the applied mixture of the polyurethane chips for 2 to 4 times with a roller of 20-30 kg and trowelling corners and edges of the applied mixture; and
hardening the pressed mixture of the polyurethane chips.
As for the photoluminescent pigment, zinc sulfide compounds are used. The pigment emits light at night by using the energy that has been accumulated during the daytime, and thus it lasts semi-permanently. This is why the photoluminescent pigment can be used in the present invention as an essential component of the noctilucent recycled waste-polyurethane chips.
Further, the roller is used in the step of pressing the layer of the waste polyurethane chips in order to secure firm binding between the waste polyurethane chips and the polyurethane binder. It is preferable that the roller is used in the temperature of 50-100xc2x0 C., the temperature in which the recycled waste-polyurethane chips and the binder do not stick to the roller.